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Advisor(s)
Abstract(s)
Microspectrophotometry (MSP) revealed the presence of a rod and at least two cone classes
(mid- and long-wavelength sensitive) in the intertidal peacock blenny Salaria pavo. Both
rhodopsin and porphyropsin based visual pigments were found in all fish, together with high
individual variation in chromophore ratio. The three morphs (females, males and sneaker
males) differed in their spectral sensitivities (as measured with the optomotor response) with
sneakers having higher sensitivity at long-wavelengths than either males or females. This longwave
displacement of peak sensitivity could be due elevated proportions of porphyropsin visual
pigments in the sneakers’ retinae. The lenses of all morphs exhibited a short-wavelength cut-off
and an unusual layer of carotenoid was found behind the retinal pigment epithelium and in the
outer segments of some cones. These screening pigments could serve a photo-protective role or
to improve visual contrast. No short-wave photoreceptors were located using MSP. This
indicates that this cone class may be absent or present at very low numbers in the retina.
This is the first in depth study of the visual system of a blenniid fish and indicates potential
within-species visual variation that may be related to the species’ habitat and morph-specific
behavioural requirements.
Description
Keywords
Intertidal fishes Light environment Microspectrophotometry Optomotor response Visual variation
Citation
Journal of Fish Biology, 65, 227-250